Muscarinic receptors are found in all parts of the human body, including the brain and salivary glands. Such receptors are members of G-protein coupled receptors, and are further divided into five subtypes (M1 to M5). Among these subtypes, M1, M2 and M3 receptors are extensively found in tissues of animal and human, and their pharmacological properties have been elucidated. Muscarinic M1 receptor is expressed mainly in cerebral cortex, and is involved in the regulation of higher cognitive functions. The M2 receptor is found mainly in heart and bladder smooth muscles, and is involved in regulation of heart rate. It is known that the M3 receptor is extensively expressed in many peripheral tissues and is involved in stimulation of the gastrointestinal tract and the urinary tract, and salivation. The M4 and M5 receptors are found in the brain, and the M4 receptor is mainly involved in movement, but the role of the M5 receptor remains obscure.
Generally, it was found that muscarinic receptor antagonists are useful for the treatment of various diseases, for example, chronic obstructive pulmonary disease, asthma, irritable bowel syndrome, urinary incontinence, rhinitis, spasmodic colitis, chronic cystitis, Alzheimer's disease, senile dementia, glaucoma, schizophrenia, gastroesophageal reflux disease, cardiac arrhythmia, and hyper-salivation syndromes (Invest. Drugs, 1997, 6 (10), 1395-1411, Drugs Future, 1997, 22 (2) 135-137, Drugs Future, 1996, 21 (11), 1105-1108, Drugs Future, 1997, 22 (7), 733-737).
Meanwhile, it is known that, among the muscarinic receptors, the M2 and M3 receptors are predominant in human bladder and play a role in the regulation of bladder contraction. The M2 receptor is present in the bladder in an amount that is at least three times larger than the M3 receptor, and it plays a role in inhibiting bladder relaxation by beta-receptor rather than being involved directly in bladder contraction. Thus, the M3 receptor appears to play the most important role in bladder contraction. Therefore, selective antagonists against the M3 receptor exhibit excellent inhibitory effects against muscarinic bladder contraction, but inhibit salivary secretion to cause dry mouth.
Accordingly, the present inventors have prepared novel derivatives that can exhibit functional activity by their selective binding to the muscarinic M3 receptor and have minimized side effects, thereby completing the present invention.